Mānuka, Leptospermum scoparium; Kānuka, Kunzea robusta

Did you notice as you tramped along the Ridge Track in East Harbour Regional Park soon after leaving the top of Wainuiomata Hill Road the variety of species of young, broadleaved trees, including five-finger and māhoe, flourishing under the canopy of the mānuka shrubland? This community of young trees, ferns, climbers etc, is a fine example of the role that mānuka, a pioneering species, plays in the regeneration of native forest on land that has been cleared by fire, by accident, or for farming.

Have you noticed the forest of very large, historic, kānuka in Wellington Botanic Garden, below the Met Office building? This is an outstanding feature of the five areas of native forest in the garden.

Mānuka is a shrub or tree, growing to 10 m tall. A NZ native, it occurs from lowland to sub-alpine areas in dry or swampy sites in the North, South, Stewart and Chatham islands. It also occurs in Australia.

Kānuka is a shrub or tree growing up to 30 m. A NZ endemic, it occurs in well-drained, lowland to montane areas on the Three Kings, and in the North and South islands. It often colonises land recovering after a fire, and, like mānuka, plays a role in the natural recovery of disturbed sites towards eventual forest. It can grow for over a century, but cannot regenerate in its own shade, so is eventually over-topped and replaced by other tree-species.
Use the table below to help distinguish mānuka from kānuka:

Feature

Leptospermum scoparium

Kunzea robusta

Part of plant

Mānuka

Kānuka

Trunk diameter

up to c. 15 cm

60 cm or more

Foliage (grasp it firmly)

prickly

not prickly

Flowers; diameter

single; c. 10 mm

in clusters; 4 – 6 mm

Seed capsules

c. 6 mm diameter; hard, woody; persist

2 – 4 mm diameter; not woody; fall off early

Capsule lids

rounded

sunken

Seeds

released in high temperatures

in same season as flowering

Mānuka is smaller than kānuka, and has larger flowers and larger seed capsules than kānuka.

Since the article was originally publised the name of kanuka has changed. What was called Kunzea ericoides in the article is now Kunzea robusta.
Kunzea robusta is the largest and most widespread of the 10 kanuka species and is the only species found in the Wellington region away from sandy coastal areas.
Kunzea ericoides is now known to be restricted to the northwest South Island.

Kunzea robusta, Kānuka Photo: Jeremy Rolfe

Kunzea robusta, Kānuka Photo: Jeremy Rolfe

Use

TTC trampers will have noticed that mānuka's strong, hard-wood, rot-resistant branches are often laid as “corduroy” on many a mucky track.

Mānuka was used by Māori for waka decking, fish hooks, fishing rods, traps for eels and other fish, garden tools, spears, clubs, and long poles, called huata used to thrust through the palisades of enemy pā. An infusion of pounded and boiled mānuka and kōwhai bark was applied to the back to ease pain. Mānuka's white gum was also used as an emollient for burns and scalds.

Captain Cook’s crew used the leaves of mānuka to make a spicy tea. In the early days of settlement in Otago, men smoked mānuka bark mixed with tea leaves, as a substitute for tobacco. Mānuka honey, which is collected from mānuka and kānuka, is dark-coloured and strongly-flavoured, however it needs to be remembered that not all varieties of mānuka have the well-known medicinal properties for which consumers are sometimes charged a premium.
Kānuka wood is very hard, so has often been used for tool handles and wharf piles. Kānuka gum mixed with oil from tītoki, was used as a perfume.

Both species have been used for firewood that produces great heat, and for fence posts. Kākāriki / parakeets use the leaves and bark of both species to rid themselves of parasites.